This is the fourth installment in Asia Times Science Editor Jonathan Tennenbaum’s series “Fusion Diary.” For an introduction to the series, readers are encouraged to start with “US abandoning its leadership in fusion energy,” by Matthew Moynihan and Alfred B Bortz. Then read part 1 of the series here, part 2 here and part 3 here.
On August 22, 2023, I interviewed Paul Methven, director of Great Britain’s Spherical Tokamak for Energy Production (STEP) program. STEP aims at building a demonstration electric power-generating fusion plant based on the spherical tokamak design.
Formerly director of submarine acquisition for the UK Defense Ministry, Methven brings with him a wealth of knowledge in organizing complex technological endeavors.
He compares the challenges of STEP to the 1960s Apollo program to land astronauts on the Moon and to the US project, led by the legendary Admiral Hyman Rickover, to build the world’s first nuclear-powered submarine. The following is the first of three parts of the interview.
Jonathan Tennenbaum: How would you describe the mission of the STEP program?
Paul Methven: The physical deliverable, if you like, is a prototype fusion energy plant. But the legacy that comes from that is probably the more important thing, which is that the plant will firstly demonstrate that you can actually make fusion energy commercially realistic, but also that through the endeavor of trying to design, deliver, operate that prototype fusion energy plant, you build a supply chain. And through that you really have the industrial capability necessary, with quite a lot of it hosted, or at least value-seeded in the UK, to service fusion programs across the globe, creating a myriad of spinoff businesses.
JT: At this point a number of countries have fusion demonstration reactor programs, generally called demos. Would you call STEP a demo in that sense?
PM: Yes, I would. But it’s a demo beyond “just” the technical aspect. I say “just” in quotation marks because this is an extraordinarily difficult thing to do. But as I say, it takes its direction from the fusion strategy that the UK government has published, which is very short document, eight pages or so, published a couple of years ago, which says, look, we intend to design and deliver a prototype fusion energy plant, and put energy on the grid. But the second goal of that is the development of a supply chain. And so our program objectives are broader than the technical.
JT: Why have you decided to build a spherical tokamak? As far as I know, the demo reactors of other countries are all large tokamaks of the “classical” sort.
PM: At the moment, the UK definitely supports being part of large-scale traditional tokamak development. I think that, in one form or another, we would wish to continue to be part of ITER and indeed to support a number of other fusion programs.
(Note: While in the European Union, Britain participated in ITER through Euratom, an organization of EU member-states. Post-Brexit, Britain is no longer a member of Euratom, and the modality of Britain’s participation in ITER has yet to be settled. – Jonathan Tennenbaum)
Because, to just put that in context, I think it’s a bit naive to suggest that there’s only one approach to fusion that could ever work. And I think, from the climate change perspective, it would be folly to only pursue one approach to fusion. It’s too important, for creating a new energy source, to blinker yourself out of everything else.
That said, we looked some time ago at the evolution of the traditional tokamak, the doughnut shape. We said, look, whilst we think technically that can work, do we think that if you merely expanded the scale of that tokamak you would get to a commercially viable proposition? We think that’s less certain.
I’m pretty sure that ITER will eventually work and demonstrate what it has to demonstrate. But if you then say I’m scaling that architecture up to commercial scale, the size of everything increases the capital cost. It is going to be pretty challenging to ultimately get return on the levelized cost of energy even in the far future.
And so we thought: is there a cheaper and therefore technically more efficient way of doing this? The UKAEA has a long history of research on the spherical tokamak stemming back to the START device, which then gave rise to MAST [Mega-Ampere Spherical Tokamak], which has then given rise to the MAST Upgrade, where we demonstrated, we believe, that you can be much more efficient with a spherical tokamak.
And now through MAST Upgrade, we demonstrated some of the critical technologies, particularly heat exhaust. That would say, yes, actually, that is a viable route. It’s an efficiency argument en route to commercial deployability that has driven the spherical tokamak pick in terms of timescales.
Now, I don’t know precisely when we’ll have this delivered and what the schedule will be. I am on the record saying that. There’s a lot of work to do, but we will drive for that target of 2040, and as we develop the details of the program, we’ll then work out exactly what is deliverable.
And that’s hugely ambitious, but represents a balance between (A) having to drive really hard, because of the climate necessity and because you have to have a unifying goal around which to drive progress across multiple organizations, and (B) keeping to something we think is potentially credible.
JT: And do you have good support from the UK government, good institutional support for this?
PM: Absolutely. As I said, STEP actually stems from the UK government fusion strategy. We’ve had really strong and consistent support from the government. Despite all the changes of personalities over the last few years, the support for the program has remained extremely strong and has grown in fact.
We can see that through the announcements that have been made, not the least of which was in October last year, the announcement of West Burton as the selected site for the STEP prototype plant. That is a really strong indication since government wouldn’t announce something like a large-scale site with the benefits that that will bring — not just globally, but in that case very locally as well – without being strongly committed
NEXT: Critical decisions on the way to fusion power
Jonathan Tennenbaum, PhD (mathematics), is a former editor of FUSION magazine and has written on a wide variety of topics in science and technology, including several books on nuclear energy.